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Monday, November 7, 2016

MOC Exam Topic: Aquaporin-4

Among the topics for the neuropathology maintenance of certification examination is aquaporin-4 (AQP-4). An important regulatory molecule in the maintenance of the proper flow of water across the blood-brain barrier, AQP-4 is the major water channel expressed within CNS astrocytic foot processes. Water flux across AQP4 is bidirectional.

2 comments:

Worth mentioning that it is the most well known target in Neuromyelitis Optica (NMO) and NMO spectrum disorders, since about 80% of patients with this syndrome will have circulating anti-aquaporin 4 antibodies. The IHC is useful when considering active NMOSD on a biopsy specimen by showing loss of staining (Neurology. 2015 Jan 13;84(2):148-58)

And one can only get so far without mentioning the glymphatic pathway..

Genetic knock-out of the gene encoding the astroglial water channel aquaporin-4, which is importantly involved in paravascular interstitial solute clearance, exacerbated glymphatic pathway dysfunction after TBI and promoted the development of neurofibrillary pathology and neurodegeneration in the post-traumatic brain. These findings suggest that chronic impairment of glymphatic pathway function after TBI may be a key factor that renders the post-traumatic brain vulnerable to tau aggregation and the onset of neurodegeneration.